A great deal of harmonization efforts have occurred among the existing aging data sets; however, the comparability of these aging surveys has not been fully articulated, calling for more deliberate efforts to establish the ex post comparability of existing aging surveys. Moreover, several countries are currently in the process of developing similar aging data sets, which creates urgency in the discussion of harmonization-what should be harmonized at the international and/or regional levels and what needs to be localized. It is increasingly recognized that cross-national comparative studies will bring new insights to our understanding of the impact of policy and institution on aging, yet only few such studies have been conducted. Therefore, we propose a series of scientific meetings (1) to enhance the ex ante comparability by bringing together the principal investigators of aging surveys who are directly connected to the creation of these data; (2) to facilitate cross-national comparative studies by discussing the ex post harmonization of aging surveys; and (3) to establish collaborations among the various aging projects by developing an international network of researchers, including both principal investigators and end users. [unreadable] [unreadable] The core activity of the proposed meeting is the bringing together of major ongoing aging research projects-both established and emerging. Established aging surveys include the Health and Retirement Study (HRS); English Longitudinal Study on Ageing (ELSA); Survey of Health, Ageing, and Retirement in Europe (SHARE); Korean Longitudinal Study on Aging (KLoSA); Strategic Advisory Group of Experts' World Health Survey (SAGE); Puerto Rican Elderly: Health Conditions (PREHCO); Mexican Health and Aging Study (MHAS); and an International Network of field sites with continuous Demographic Evaluation of Populations and Their Health in developing countries (INDEPTH). We will also invite the PIs of emerging aging surveys in Japan, China, Thailand, and Taiwan; experts in the survey methodology; and researchers who have conducted such studies. Methodological expertise is needed to achieve high data quality and comparability, and spreading state-of-art methods to newly formed social surveys would greatly improve data quality both of new surveys and comparatively. [unreadable] [unreadable] We propose the first meeting to be held in Chiang Mai, Thailand, from February 21 to 24, 2007. This location has been chosen for both scientific and pragmatic reasons. First, several Asian countries are currently developing an HRS-like survey, including Thailand, Japan, China, and Taiwan. The Japanese survey will be collecting its baseline data later this year, while the Thailand team targets collecting its baseline data in 2007. Considering the developmental stages of these surveys and the pragmatic consideration of meeting costs, Thailand seems to be the best choice. [unreadable] [unreadable] The National Institute on Aging's (NIA) Behavioral and Social Research Program (BSR) has identified the development of international networks in population aging as one of the major areas of emphasis in extramural funding and solicits proposals for such development activities. The NIA specifically calls for the "development of methodologies and mechanisms that facilitate the harmonization (or, in some cases, the standardization) of data collected in both industrialized and less developed countries; and development of methods for calibrating health and well-being across populations." BSR currently has a research portfolio on data collection that spends $30-40 million per year on data collection alone. Considering such significant investment in aging surveys, the benefits of this harmonization meeting of aging surveys greatly exceed its costs. [unreadable] [unreadable] [unreadable]